There is a jewelry show coming up next week at the Mirage. Many grey market dealers will be there. I remember there being alot from NYC & LA> Call the Mirage & ask if you can get a list of jewelers that will be at the show. Then call around. You will get your best deal if you see them in person. They know you are serious, not just a tire kicker. And then you can nego with them. Once you have the relationship established, you can request items.
I don't see why a dealer would buy watches unless the cert is filled out. There would be no buyers for them to sell the watches to. People are looking for a better buy than the AD, not to get taken.
I know some diamond brokers can also get grey market watches.
Stay away from the black market.